REVENUE RECOGNITION AND RELATED ALLOWANCES - Accruals and Allowances (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	$ 59,946
Ending balance	72,469
Chargebacks
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	49,882	$ 39,007
Accruals/Adjustments	181,986	120,706
Credits Taken Against Reserve	(169,345)	(122,344)
Ending balance	62,523	37,369
Government Rebates
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	8,901	8,974
Accruals/Adjustments	7,519	7,650
Credits Taken Against Reserve	(6,703)	(5,681)
Ending balance	9,717	10,943
Returns
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	16,595	12,552
Accruals/Adjustments	14,103	8,248
Credits Taken Against Reserve	(10,695)	(6,144)
Ending balance	20,003	14,656
Administrative Fees and Other Rebates
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	8,281	7,353
Accruals/Adjustments	17,392	17,123
Credits Taken Against Reserve	(17,161)	(16,971)
Ending balance	8,512	7,505
Prompt Payment Discounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	2,549	2,009
Accruals/Adjustments	6,551	5,174
Credits Taken Against Reserve	(6,277)	(4,909)
Ending balance	$ 2,823	$ 2,274